Real time scanning surveillance radar systems can be used in many commercial applications, such as automotive radar and human feature extraction. Typical scanning radars often operate under the constraint of only a limited number of pulses, thus real time estimation and detection of radar targets are quite difficult due to short dwell time (i.e., the time that an antenna beam spends on a target). Moreover, as modern radar systems are becoming increasingly sophisticated, systems with low hardware complexity and low cost while still achieving comparable high range and speed accuracy and high resolution are in strong demand.
For modern radars, frequency or phase modulation is normally needed to achieve desired radar performance. For example, the Frequency Modulated Continuous Wave (FMCW) technique is widely used due to its good range and velocity resolution. However its resolution is inversely proportional to the signal bandwidth and it requires a long sampling window, hence a long dwell time, to complete a range measurement.
Furthermore, FMCW radars usually use Fast Fourier Transform (FFT) to estimate Doppler frequencies, which results in high hardware complexity and high power consumption. The Multi Frequency Continuous Wave (MFCW) is another modulation scheme that continuously transmits multiple frequency tones in parallel with each other. The phases of the returned signals are compared to obtain a range estimate. This technique allows a really short dwell time and a very small signal bandwidth. However, one transceiver is needed for each frequency tone, making the MFCW radar very costly in implementation and not suitable for large-scale phased array integration. Prior work on radar modulation schemes such as the above-mentioned FMCW and MFCW still face the challenges of balancing trade-offs of excellent radar performance against high hardware complexity and cost.
Accordingly, there is a need for improved radar modulation formats and signal processing.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.